Moisture resistant multiwall bags



Feb. 5, 1963 J. w. MEANS ETAL 3,076,592 MOISTURE RESISTANT- MULTIWALLBAGS Filed Jan. 16, 1961 JOHN WhMEA/vs ALLEN DANIELS BY M M UnitedStates Patent Ofiice 3,076,592 MOISTURE RESISTANT MULTIWALL BAGS John W.Means, Cleveland Heights, and Allen Daniels, Cleveland, Ohio, assignorsto Chase Bag Company, a corporation of Delaware Filed Jan. 16, 1961,Ser. No. 82,908 2 Claims. (Cl. 229-55) The present invention relates toa multi-wall bag having a freely supported elastic moisture resistantintermediate ply, and it consists in the combinations, constructions andarrangements of parts hereinafter described and claimed. It should beunderstood that this pertains to both sewn and pasted-end type'multiwallbags made either in open mouth or valve form.

Generally there is provided a shipping bag formed of a plurality ofpaper laminae spot adhered to each other and to a circumferentiallycontinuous intermediate lamina of elastic moisture resistantmiiterial,such as polyethylone, relatively freely supported between itsimmediately adjacent lining andsurrounding': protective paper laminae.

In the past,moisture barrier materials coated on or bondedly laminatedwith paper have been considered to be the most economical and mostpractical way of providing moisture protection in a multi-wall bag. Theapplicants discovered that polyethylene film of a thickness sufiicientto provide a given degree of moisture protection plus a ply of kraftpaper was considerably less expensive than an equal amount ofpolyethylene coated on the same paper. This observation led to thedevelopment of the herein disclosed and claimed bag which consists of arelatively freely supported polyethylene film con- 'stituting one of theplies of a multi-wall bag plus one ;ply of paper in place of a coated orlaminated sheet of equivalent strength and moisture barrier properties.

The advantages of this design over a polyethylene coated paper are:lower cost, film-to-film contact on the longitudinal seam for bettermoisture protection, and the fact that breakage of the paper plies canoccur without rupturing the somewhat elastic polyethylene ply, thus preventing the contents of the bag. from spilling out. In the case ofpolyethylene coated paper, the paper and the polyethylene coating alwaysbreak at the same time.

'It is accordingly a principal object of the invention to provide amulti-wall bag having a relatively freely supported elastic moistureresistant intermediate ply, whereby the contents are protected againstmoisture penetration and/or spillage through breaks in the paperlaminae.

It is another object to provide a bag of this type in which the moistureresistant ply is continuous, to obviate the seepage that heretoforeoccurred at the longitudinal seams of coated or laminated moisturebarrier liners.

It is a further object to provide a bag of the character described thatcan be made on conventional multi-wall bag machines.

It is the overall object to provide a shipping bag of the nature setforth which is simple in construction, inexexpensive to manufacture andyet effective and eflicient in use.

Other and further objects of the invention will become apparent from areading of the following specification :taken in conjunction with thedrawing, in which:

T FIGURE 1 is a fragmentary partially exploded perspective view of apreferred embodiment of the invention,

FIGURE 2 is a fragmentary plan view of an edge of the assembled bag ofFIGURE 1,

FIGURE 3 is an isometric view of a bag embodying the invention, and

FIGURE 4 is a fragmentary view similar to FIGURE .3 but showing amodified form of the invention.

With reference now to the drawing, the numeral 3,076,592 Patented Feb.5, 1953 generally designates the multi-wall bag which may be sewn withan adhesively secured strip thereover at its closed end, as shown in 10ain FIGURE 3 or the closed end may be a pasted-end valved type asindicated at 10b in FIGURE 4. Bag 10 comprises an outer ply 11 of paperof desired strength and appearance, the latter including finish,coloration, printing matter, etc. Ply 11 has an overlapped adheredconventional seam 12. Ply 11 is herein shown as being lined by anotherlamina 13, held assembled therewith by spots 14 of adhesive materiallocated at widely spaced points along or relatively close to the uppermargin of the laminae 11, and 13.

The next ply 15 is a sheet of polyethylene or equivalent elastic andmoisture resistant material. Ply 15 is similarly adhered along its uppermargin or relatively close thereto, to the lamina 13 by spots 16 ofsuitable adhesive material. The ply 15 has a plastic-to-plastic seam 16(FIG. 2) which prevents any seepage of moisture into or from the bag 10(as would occur where the lamina 15 is formed of plastic-impregnated orcoated paper, or paper laminated with a film of plastic material, as inthe prior art). The moisture barrier ply 15 is lined by one or moreplies'17 and 18 of paper. Plies 17 and 18 are similarly adhered to thefilm 15 and to each other by spots of adhesive material as indicated at19.

As best seen in FIGURE 2, the overlapped seams 12 and 16', whichrespectively make the laminae 11 and 15 circumferentially continuous,and the seams 20, 21 and 22, which join the mating edges respectively ofthe laminae 13, 17 and 18, are all disposed in somewhat offsetarrangement circumferentially of the bag to prevent objectionablethickening of the bag walls, as would occur if the seams weresuperimposed relative to one or more other seams. serrated edge formedon each and all of the laminae.

While but one form of the invention has been shown and described herein,it will be readily apparent to those skilled in the art that many minormodifications may be made without departing from the spirit of theinvention or the scope of the appended claims.

What is claimed is:

1. A multiwall bag, comprising: at least one outer lamina of flexibleand relatively inelastic paper, at least one inner lamina of relativelyinelastic paper, and an intermediate lamina of somewhat elastic moistureresistant plastic sheet material, said laminae being free of attachmentto each other throughout the side wall areas thereof, said intermediatelamina being attached to the inner and outer layers by means of spacedspots of adhesive adjacent the free upper edges thereof providingrelatively free movement of substantially all of the surface of saidintermediate lamina over the surfaces of the other laminae engaging thesame to minimize the danger of simultaneous rupturing of all of saidlaminae by bag damaging forces.

2. A bag according to claim 1, said somewhat elastic plastic sheetmaterial being polyethylene.

References Cited in the file of this patent UNITED STATES PATENTS1,922,867 Rosmait Aug. 15, 1933 2,042,594 Fry et al June 2, 19362,157,392 Williams May 9, 1939 2,493,349 Hoppe Jan. 3, 1950 2,496,796Kardon Feb. 7, 1950 2,751,140 Brady June 19, 1956 FOREIGN. PATENTS531,463 Great Britain Jan. 3, 1941 The numeral 23 designates the

1. A MULTIWALL BAG, COMPRISING: AT LEAST ONE OUTER LAMINA OF FLEXIBLEAND RELATIVELY INELASTIC PAPER, AT LEAST ONE INNER LAMINA OF RELATIVELYINELASTIC PAPER, AND AN INTERMEDIATE LAMINA OF SOMEWHAT ELASTIC MOISTURERESISTANT PLASTIC SHEET MATERIAL, SAID LAMINAE BEING FREE OF ATTACHMENTTO EACH OTHER THROUGHOUT THE SIDE WALL AREAS THEREOF, SAID INTERMEDIATELAMINA BEING ATTACHED TO THE INNER AND OUTER LAYERS BY MEANS OF SPACEDSPOTS OF ADHESIVE ADJACENT THE FREE UPPER EDGES THEREOF PROVIDINGRELATIVELY FREE MOVEMENT OF SUBSTANTIALLY ALL OF THE SURFACE OF SAIDINTERMEDIATE LAMINA OVER THE SURFACES OF THE OTHER LAMINAE ENGAGING THESAME TO MINIMIZE THE DANGER OF SIMULTANEOUS RUPTURING OF ALL OF SAIDLAMINAE BY BAG DAMAGING FORCES.